Avalanche Forecast

Dry cool conditions persist as a ridge builds over the region.

SATURDAY NIGHT: Cloudy with some isolated flurries and trace amounts of snow, light southwest wind, temperatures around -8 C.

SUNDAY: Cloudy with some sunny breaks in the afternoon, moderate southwest wind, temperatures around -6 C.

MONDAY: Mix of sun and cloud, moderate west wind, temperatures around -8 C.

TUESDAY NIGHT: Sunny, light to moderate southwest wind, temperatures around -10 C.

Few avalanches have been reported since last weekend, partly due to low observer numbers and/or suggesting a trend towards a low probability/high consequence scenario for the persistent slab avalanche problem.

There were many notable avalanches between Dec 18-20 including natural, accidental, and remotely triggered avalanches up to size 2.5 at Pine Pass (one party of three was caught with two individuals partially buried and one fully buried) and large natural avalanches at Torpy and Tumbler Ridge. Many of these avalanches ran on 30-80 cm deep persistent weak layers, so although these reports are a week old, they are still significant when dealing with a persistent slab avalanche problem.

Exposed higher elevations in the region have been significantly wind affected, and more wind is expected over the next few days. As a result, new and recent wind slabs are suspected to exist across most aspects in the alpine and upper treeline.

In more sheltered areas, 30-50 cm of snow has been settling above a variable mix of weak layers. Depending on location in the region, aspect, and elevation, these weak layers may appear as surface hoar (think shaded sheltered spots) or as a combination of crusts and facets (think of areas that may have been exposed to sun or rain). Reactivity at these interfaces has been variable. There has been compelling evidence these weak layers are widespread around Pine Pass, the McGregors, Hasler, and Tumbler Ridge. There has been less evidence around McBride and Renshaw, however our field team has found them in some isolated areas near McBride so we can not consider them entirely absent. We have little information from Kakwa.

A basal crust from November exists near the bottom of the snowpack in most areas. This crust may be a concern in shallow snowpack areas as well as in wind affected, thin-to-thick snowpack transition zones in the alpine.

Snow depths are in the 180-250 cm range around Pine Pass, the McGregors, and McBride and closer to 120-150 cm in the Tumbler Ridge area.

• Use careful route-finding and stick to moderate slope angles with low consequences.
• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
• Watch for areas of hard wind slab on alpine features.